Asthma is a serious public health problem in the US that affects one in ten schoolchildren and causes ~500,000 hospitalizations each year, with an estimated economic cost of $56 billion. Allergic sensitization to household allergens (dust mites, cat, dog, mouse, cockroach, molds) is a major risk factor for the development of asthma. Asthma in early childhood can also be influenced by exposure to bacterial products which may potentiate or have protective effects depending on the level of environmental exposure and genetic factors. Recent studies in a mouse model have shown that the bacterial protein, flagellin, promotes allergic sensitization to indoor allergens and that human patients with asthma have high levels of antibodies to flagellin. Household dust samples have been shown to contain flagellin. However, investigation of the association between exposure to flagellin and asthma requires a robust test to measure flagellin in environmental samples from homes and public buildings. The goal of this SBIR Phase I project is to develop a high throughput immunoassay for flagellin, capable of analyzing several hundred samples per week. The specific aims of the project are i) to purify flagellin from Pseudomonas aeruginosa; ii) to develop a monoclonal or polyclonal antibody based immunoassay which detects flagellin from most bacterial species; iii) to validate the assay performance to measure flagellin in dust samples of known allergen and endotoxin content. The strategy involves developing a multiplexed immunoassay which can be used to measure flagellin, allergens and molds simultaneously. This assay will be to assess the role of flagellin exposure in allergic disease. Commercial potential: Successful completion of this SBIR will result in valuable immunoassay product(s) that can be marketed by the applicant, Indoor Biotechnologies, to allergy/immunology researchers in academia, government agencies, pharmaceutical companies and vaccine manufacturers, worldwide. The research could generate several product lines that are complementary to the company's current products and which will enable the company to expand its product range in new markets.